LED Sensing Circuit Noise Reduction via Calibration
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Solution Overview
Problem
Electronic display devices, such as those using OLEDs or μLEDs, face challenges in maintaining consistent gray levels across pixels due to noise in the sensing circuits, leading to visual display artifacts from inconsistent color emission.
Innovation Solution
A calibration system that filters noise in the electrical signals by using techniques such as averaging voltage samples, ramp digital-to-analog converter signals, and time-to-digital conversion to determine accurate voltage values for calibrating pixels, ensuring uniform gray level output across the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple voltage samples are taken and averaged to reduce noise, then measurement precision is improved, but loss of time increases due to multiple sampling operations
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor to a known voltage level before the sensing operation. This preparation step allows the capacitor to be ready for immediate voltage comparison with the pixel, enabling faster sampling without sacrificing measurement precision. The capacitor is charged to a voltage that is expected to be close to the pixel voltage, reducing the time needed for accurate measurement.
Solution Approach 2:
The patent implements periodic action through repeated sampling cycles where the capacitor is periodically charged and discharged multiple times to obtain multiple voltage samples. These periodic sampling operations allow for statistical averaging to reduce noise, improving measurement precision while managing the time trade-off through efficient periodic execution rather than continuous operation.
2Measurement precision
If the capacitor is charged to a high voltage to ensure accurate sensing, then measurement precision is improved, but use of energy increases due to frequent charging operations
Solution Approach 1:
The patent applies local quality by charging the capacitor to different voltage levels depending on the specific pixel and its characteristics. Rather than always charging to the maximum voltage, the system adjusts the charging voltage locally based on the expected pixel voltage range, ensuring sufficient measurement precision while minimizing unnecessary energy consumption from over-charging.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the capacitor charging voltage based on the pixel being measured. The charging voltage parameter is modified to match the expected voltage range of different pixels, allowing accurate sensing while optimizing energy usage. This adaptive parameter adjustment prevents wasteful energy consumption from consistently using high charging voltages.
Data Source
AI summary
Systems, methods, and devices are provided to reduce noise present in sensing circuits used for calibrating light emitting diodes (e.g., organic light emitting diodes) in electronic display devices. Such a system may include a display that renders image data using self-emissive pixels. Values on the pixels may be sensed using a current source that outputs a current and a comparator that receives the current. The comparator changes states when a voltage signal output by the capacitor crosses a first threshold voltage or a second threshold voltage. A controller receives a first time when the comparator component changes states based on the voltage signal, receives a second time when the comparator component changes states based on the voltage signal, determines a current value based on the first time and the second time, and calibrates a pixel based on the current value.